"We find that when no penalty is assessed for a wrong answer, all test-takers answer every question. But, when there is a small penalty for wrong answers and the task is explicitly framed as an SAT, women answer significantly fewer questions than men."

http://freakonomics.com/2011/11/18/sat-strategy-by-gender-me...

Retaking the test: http://philvol.sanford.duke.edu/documents/SAN01-20.pdf

PS: Making an unbiased test is really hard, the SAT comes reasonably it’s not there.